1. Field of the Invention
The present invention relates to a Hall element composed of n-type Si, and particularly to a Si Hall element having a very low unbalanced voltage.
2. Brief Description of the Prior Art
Hitherto, in many cases, a Hall element was composed of a thin rectangular semiconductor plate, near two opposite edges of which the current electrodes having lengths approximately equal to that of the edges are attached, and at the centers of the other two opposite edges Hall voltage electrodes of small size are attached for the purpose of picking up the output signal. Under ideal conditions, when no magnetic field is applied, no output voltage arises at the Hall voltage electrodes even when a current is applied at the current electrodes.
However, practically speaking, because of lack of uniformity of the current density caused by lack of uniformity of the semiconductor material, lack of uniformity of the element thickness and/or unsatisfactory location of the electrode, an unbalanced voltage, namely the Hall voltage, arises at the output electrodes even when no magnetic field is applied; and an error thereby arises. Recently, owing to great advancements on the technical side of integrated circuit manufacture, the inherent unbalanced voltage of the Hall element, i.e. the unbalanced voltage of a Hall element included in a bare pellet, has been considerably lowered. On the other hand, because of the piezo-resistive effect, it is unavoidable that the unbalanced voltage will increase markedly when a pellet including the Hall element is packaged, that is when the pellet is bonded to a metallic frame, the lead wire is attached and then this pellet is moulded with resin thereby generating a thermal strain and a mechanical strain in the pellet. For this reason, for example, even though a brushless d.c. motor, to which the IC (integrated circuit) having a Si Hall element is attached has theoretical advantages, it has hitherto been difficult to put this motor to practical use.